- Visible light photocatalytic one pot synthesis of: Z -arylvinyl halides from e -arylvinyl acids with N -halosuccinimide
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An efficient visible light photocatalytic strategy to synthesize thermodynamically less stable Z-arylvinyl halides (with up to >99/1 Z/E ratio and 86% yield) was developed. The reaction combined base-mediated halodecarboxylation of E-arylvinyl acids with N-halosuccinimide and visible light Ir-photocatalyzed isomerization of E-arylvinyl halides in a one pot sequential catalytic process. This journal is
- Wong, Man-Kin,Xu, Cai Feng,Yu, Kun Yi,Yu, Qiong
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p. 3931 - 3934
(2022/02/16)
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- The hydrodebromination of 1,1-dibromoalkenes via visible light catalysis
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Vinyl bromides are versatile synthetic intermediates and widely applied in organic synthesis and pharmaceuticals. Herein, a hydrodebromination reaction of 1,1-dibromoalkenes was established via visible light catalysis. A variety of structurally different vinyl bromides were obtained in moderate to excellent yields.
- Sun, Wencheng,Teng, Qiaoling,Cheng, Dongping,Li, Xiaonian,Xu, Xiaoliang
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supporting information
(2019/12/05)
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- Highly selective hydrosilylation of equilibrating allylic azides
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The Pt-catalyzed hydrosilylation of equilibrating allylic azides is reported. The reaction provides only one out of four possible hydrosilylation products in good yields and with very high chemoselectivity (alk-1-enevs.alk-2-ene), regioselectivity (linearvs.branched), and excellent functional group tolerance.
- Liu, Ruzhang,Liu, Yongmei,Wang, Juan,Wei, Zhen,Xue, Huaiguo
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supporting information
p. 5038 - 5041
(2020/05/18)
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- Photocatalytic Isomerization of Styrenyl Halides: Stereodivergent Synthesis of Functionalized Alkenes
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An efficient and general method for the isomerization of styrenyl halides under different photocatalytic conditions (fac-Ir(ppy)3 in methanol for E to Z isomerization and fluorescein in 1,4-dioxane for Z to E isomerization, respectively) is disclosed. A series of stereospecific transformations constitute preliminary validation of this strategy in the synthesis of functionalized alkenes, including two diaryl alkenes, a styrenyl boronic ester and an enyne. The photocatalytic isomerization and subsequent cross coupling reaction can be run in a one-pot manner. The stereodivergent synthesis of all four isomers of a conjugated diene, as well as the antitumor agent DMU-212 and its (Z)-isomer highlights the synthetic applicability of this method.
- Zhang, Hao,Xu, Qing,Yu, Lei,Yu, Shouyun
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supporting information
p. 1472 - 1477
(2019/11/03)
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- Nickel-Catalyzed Reductive Cross-Coupling of Vinyl Bromides with Unactivated Alkyl Halides
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The use of pyridine as the sole ligand for the reductive vinylation of unactivated secondary alkyl halides under Ni-catalyzed conditions has been developed. Both alkyl- and aryl-substituted vinyl bromides are suitable, in which alkyl-decorated α-alkenyl bromides resulted in the α-products in good results.
- Gu, Jun,Qiu, Canbin,Lu, Wenbin,Qian, Qun,Lin, Kunhua,Gong, Hegui
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supporting information
p. 1867 - 1873
(2017/04/06)
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- Nickel(II)-magnesium-catalyzed cross-coupling of 1,1-dibromo-1-alkenes with diphenylphosphine oxide: One-pot synthesis of (E)-1-alkenylphosphine oxides or bisphosphine oxides
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A novel nickel(II)-magnesium-mediated cross-coupling of diphenylphosphine oxide with a variety of 1,1-dibromo-1-alkenes has been developed, which provides a powerful and general methodology for the stereoselective synthesis of various (E)-1-alkenylphosphine oxides or bisphosphine oxides, with operational simplicity of the procedure, good to high yields and broad substrate applicability. Mechanistic studies reveal that the reaction might involve a Hirao reduction, cross-coupling and Michael addition. Copyright
- Liu, Liu,Wang, Yulei,Zeng, Zhiping,Xu, Pengxiang,Gao, Yuxing,Yin, Yingwu,Zhao, Yufen
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supporting information
p. 659 - 666
(2013/04/10)
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- Conformationally restricted pyrrolidines by intramolecular [2+2] photocycloaddition reactions
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Intramolecular [2+2] photocycloaddition reactions of diversely substituted N-Boc protected 4-(allylaminomethyl)-2(5H)-furanones resulted in rigid products (53-75%) with three spatially defined positions for further functionalisation. The Royal Society of Chemistry.
- Fort, Diego A.,Woltering, Thomas J.,Nettekoven, Matthias,Knust, Henner,Bach, Thorsten
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supporting information
p. 2989 - 2991
(2013/05/09)
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- Efficient halogenation of unsaturated organoaluminum compounds with sulfonyl halides
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Alkenylalumanes prepared by carbo-or cycloalumination of substituted acetylenes reacted with an equivalent amount of sulfonyl halide (MsCl, TsCl, PhSO2Cl, MsBr) in methylene chloride or hexane at room temperature to produce alkenyl halides in high yields. Electron-donor solvents such as diethyl ether or tetrahydrofuran inhibited the halogenation process. β-Substituted vinylalumanes generated by hydroalumination of substituted acetylenes failed to react with sulfonyl halides.
- Ramazanov,Kadikova,Dzhemilev
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p. 321 - 326
(2013/07/26)
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- Syntheses of strychnine, norfluorocurarine, dehydrodesacetylretuline, and valparicine enabled by intramolecular cycloadditions of Zincke aldehydes
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A full account of the development of the base-mediated intramolecular Diels-Alder cycloadditions of tryptamine-derived Zincke aldehydes is described. This important complexity-generating transformation provides the tetracyclic core of many indole monoterpene alkaloids in only three steps from commercially available starting materials and played a key role in short syntheses of norfluorocurarine (five steps), dehydrodesacetylretuline (six steps), valparicine (seven steps), and strychnine (six steps). Reasonable mechanistic possibilities for this reaction, a surprisingly facile dimerization of the products, and an unexpected cycloreversion to regenerate Zincke aldehydes under specific conditions are also discussed.
- Martin, David B. C.,Nguyen, Lucas Q.,Vanderwal, Christopher D.
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experimental part
p. 17 - 46
(2012/02/04)
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- NOVEL POLYMERIZABLE MONOMER, AND MATERIAL FOR ORGANIC DEVICE, HOLE INJECTION/TRANSPORT MATERIAL, MATERIAL FOR ORGANIC ELECTROLUMINESCENT ELEMENT AND ORGANIC ELECTROLUMINESCENT ELEMENT EACH COMPRISING POLYMER (POLYMERIC COMPOUND) OF THE POLYMERIZABLE MONOMER
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A polymerizable monomer represented by the following formula (1) wherein at least one of Ar1 to Ar3 is substituted by a group represented by the following formula (2) and which is substituted by one or more groups comprising a polymerizable functional group. Ar1 to Ar3 are a substituted or unsubstituted aryl group having 6 to 40 ring carbon atoms, Ar6 is a substituted or unsubstituted aryl group having 6 to 40 ring carbon atoms and Ar4 and Ar5 are a substituted or unsubstituted arylene group having 6 to 40 ring carbon atoms.
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- Synthesis of (±)-1-phenyl-2-azabicyclo[2.2.1]heptane derivatives - Novel NK1 receptor ligands
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The synthesis of the 1-phenyl-2-azabicyclo[2.2.1]heptane derivative 2, a potential NK1 receptor ligand, is reported. Ring-closing metathesis of diene 10 and regio- and stereoselective opening of the oxirane ring in 14 are key steps in the synth
- Raubo, Piotr,Kulagowski, Janusz J.,Chicchi, Gary G.
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p. 271 - 274
(2007/10/03)
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- NOVEL PHOTOINITIATORS AND THEIR APPLICATIONS
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Photoinitiators of formula (Ia) or (Ib) having chain transfer groups, wherein n is 1 or 2; PI is for example a group of formula (IIa); PI' inter alia is a group of formula (IIIa); Ar is for example phenyl; Ar2 is inter alia phenylene; R1 and R2 are for ex
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Page/Page column 20
(2010/11/24)
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- Photochemical generation of highly destabilized vinyl cations: The effects of α- and β-trifluoromethyl versus α- and β-methyl substituents
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(Chemical Equation Presented). The photochemical reactions in methanol of the vinylic halides 1-4, halostyrenes with a methyl or a trifluoromethyl substituent at the α- or β-position, have been investigated quantitatively. Next to E/Z isomerization, the reactions are formation of vinyl radicals, leading to reductive dehalogenation products, and formation of vinyl cations, leading to elimination, nucleophilic substitution, and rearrangement products. The vinyl cations are parts of tight ion pairs with halide as the counterion. The elimination products are the result of β-proton loss from the primarily generated α-CH3 and α-CF3 vinyl cations, or from the α-CH3 vinyl cation formed from the β-CH3 vinyl cation via a 1,2-phenyl shift. The β-CF 3 vinyl cation reacts with methanol yielding nucleophilic substitution products, no migration of the phenyl ring producing the α-CF3 vinyl cation occurs. The α-CF3 vinyl cation, which is the most destabilized vinyl cation generated thus far, gives a 1,2-fluorine shift in competition with proton loss. The experimentally derived order of stabilization of the vinyl cations photogenerated in this study, α-CF3 3 3 3, is corroborated by quantum chemical calculations, provided the effect of solvent is taken into account.
- Van Alem, Kaj,Belder, Geerte,Lodder, Gerrit,Zuilhof, Han
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p. 179 - 190
(2007/10/03)
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- New synthesis of vaulted biaryl ligands via the Snieckus phenol synthesis
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(Chemical Equation Presented) In an effort to develop a synthesis of the VAPOL ligand that avoids the use of a chromium carbene complex, a route was examined that involved the annulation of a naphthalene carboxamide via the method of Snieckus. The latter
- Yu, Su,Rabalakos, Constantinos,Mitchell, William D.,Wulff, William D.
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p. 367 - 369
(2007/10/03)
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- Formation of nanoarchitectures including subnanometer palladium clusters and their use as highly active catalysts
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Subnanometer Pd clusters stabilized within micelles of random copolymers were formed by direct immobilization of Pd(0) via ligand exchange. The clusters were estimated to contain approximately seven Pd atoms on average (cluster diameter ≈ 0.7 nm). Several
- Okamoto, Kuniaki,Akiyama, Ryo,Yoshida, Hisao,Yoshida, Tomoko,Kobayashi, Shu
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p. 2125 - 2135
(2007/10/03)
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- Polymer-micelle incarcerated ruthenium catalysts for oxidation of alcohols and sulfides
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Highly active immobilized ruthenium catalysts, which can be used for oxidation of alcohols and sulfides, were developed on the basis of the polymer-micelle incarcerated (PMI) method. The catalysts could be recovered and reused several times without loss of activity and no metal leaching was observed. Selection of micelle-forming conditions and polymer structures were key in achieving high activities. TEM and SEM analyses were conducted to observe the structures of PMI-Ru.
- Miyamura, Hiroyuki,Akiyama, Ryo,Ishida, Tasuku,Matsubara, Ryosuke,Takeuchi, Masahiro,Kobayashi, Shu
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p. 12177 - 12185
(2007/10/03)
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- CYSTEINE PROTEASE INHIBITORS
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The present invention is directed to compounds that are inhibitors of cysteine protease, in particular, cathepsins B, K, L, F, and S and are therefore useful in treating diseases mediated by these proteases. The present invention is directed to pharmaceut
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Page/Page column 49
(2010/02/07)
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- A stable β-silyl carbocation with allyl conjugation
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Phenyl group replaced by a double bond yielding a stable β-silyl carbocation was studied. Two systems were examined in which positive charge could be stabilized by one phenyl and one double bond or two double bonds. The carbocation was found to be stable at room temperature with tetrakis(pentafluorophenyl)borate as the anion benzene as the solvents. The range of β-silyl carbocations observed under stable ion conditions was relatively circumscribed.
- Lambert, Joseph B.,Liu, Chunqing,Kouliev, Timur
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p. 667 - 671
(2007/10/03)
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- Catalytic Hunsdiecker reaction and one-pot catalytic Hunsdiecker-Heck strategy: Synthesis of α,β-unsaturated aromatic halides, α- (dihalomethyl)benzenemethanols, 5-aryl-2,4-pentadienoic acids, dienoates and dienamides
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The reaction of α,β-unsaturated aromatic (or heteroaromatic) carboxylic acids with N-halosuccinimides (1 equiv.) and catalytic tetrabutylammonium trifluoroacetate (0.2 equiv.) in dichloroethane results in facile halodecarboxylation affording the corresponding (E)-halides in good to excellent yields. A similar reaction, but with 2 equiv. of N-halosuccinimides in acetonitrile-water (1:1 v/v) results in the exclusive formation of the corresponding α-(dihalomethyl)benzenemethanols. Furthermore, a one-pot strategy has been developed combining catalytic Hunsdiecker reaction (using tetrabutylammonium trifluoroacetate in dichloroethane) and Heck coupling (using palladium acetate/triethylamine/triphenylantimony/dichloroethane) for the synthesis of 5-aryl-2,4-pentadienoic acids, esters and amides in moderate to good yields. The natural product piperine and pipergualamine has been synthesized via the above route. Mechanistic and theoretical studies (via AM1 calculations) provide a useful insight into the mechanism of the present halodecarboxylation reaction, suggesting an ionic pathway involving the attack of the halogenium ion across the carbon-carbon double bond, triggering the elimination of carbon dioxide. (C) 2000 Elsevier Science Ltd.
- Naskar, Dinabandhu,Roy, Sujit
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p. 1369 - 1377
(2007/10/03)
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- Stereoselective synthesis of (E)-β-arylvinyl halides by microwave-induced Hunsdiecker reaction
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(E)-β-Arylvinyl halides were prepared in high yields in a short reaction (1-2 min) by microwave irradiation of the corresponding 3-arylpropenoic acids in the presence of N-halosuccinimide and catalytic LiOAc.
- Kuang,Senboku,Tokuda
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p. 1439 - 1442
(2007/10/03)
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- Catalytic processes of oxidation by hydrogen peroxide in the presence of Br2 or HBr. Mechanism and synthetic applications
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The mechanism and the synthetic applications for the oxidation of alcohols, ethers, and aldehydes by H2O2 catalyzed by Bf2 or Br- in a liquid two-phase system (aqueous and organic) are reported. Aliphatic and benzylic primary alcohols and ethers show an opposite behavior, which has been rationalized on the ground of the different electronic configurations of the intermediate alkyl (π-type) and acyl (σ-type) radicals and their influence on enthalpic and polar effects. A two-phase system is particularly useful also for an efficient benzylic bromination by Br2 or Br-; the substitution of the benzyl bromide by OH, OR, and OCOR regenerates Br-, which can be recycled. The evaluation of the relative reactivities of the involved substrates and intermediates has allowed to develop a variety of simple, facile, convenient, and selective syntheses of alcohols, aldehydes, ketones, esters, and benzyl bromides, which fulfill the conditions for practical applications.
- Amati, Alessandro,Dosualdo, Gabriele,Zhao, Lihua,Bravo, Anna,Fontana, Francesca,Minisci, Francesco,Bjorsvik, Hans-Rene
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p. 261 - 269
(2013/09/08)
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- Stereoselective hydrogenolysis of 1,1-dibromo-1-alkenes and stereospecific synthesis of conjugated (Z)-alkenyl compounds
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The Pd-catalyzed hydrogenolysis of 1,1-dibromoalkenes with Bu3SnH occurs at room temperature stereoselectively to give (Z)-1-bromo-1-alkenes. We sought to determine the optimal reaction conditions and illustrate the scope of this method with 32 dibromoalkenes including alkenyl- and alkynyl- conjugated 1,1-dibromo-1-alkenes 7a-h and 2,2-disubstituted 1,1-dibromo-1- alkenes 9af. Triphenylphosphine was the best ligand for the Pd-catalyzed hydrogenolysis. A wide range of solvents can be used for this reaction excluding EtOH, AcOH, and CHCl3. However, the reaction proceeds even in these solvents with the addition of a cosolvent or radical scavenger. The reaction of 1,1-diiodo-1-alkene (3) gave a mixture of (Z)-1-iodo-1-alkene (4), (Z)-1-tributylstannyl-1-alkene (5), and a terminal alkene 6, while that of 1,1-dichloroalkene did not occur. This selectivity can be explained by the stereoselective insertion of Pd(0) to a trans bromine-alkenyl carbon bond, successive transmetalation with Bu3SnH, and reductive elimination. The Suzuki and Sonogashira couplings of the resulting (Z)-1-bromo-1-alkenes with alkenyl(dialkoxy)borane and terminal alkyne occurred to give conjugated polyenes and enynes stereospecifically. The Pd-catalyzed hydrogenolysis of 1,1-dibromo-1-alkene and successive cross-coupling can be carried out either in a stepwise manner or in one-pot under the same Pd catalysis. These two processes should be useful for the synthesis of geometrically pure polyene and enyne with a Z-alkenyl unit.
- Uenishi, Jun'ichi,Kawahama, Reiko,Yonemitsu, Osamu,Tsuji, Jiro
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p. 8965 - 8975
(2007/10/03)
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- Conjugative interaction in styrenes
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Conjugative interactions of the carbon-carbon double bond are fundamental in organic chemistry. In this work, equilibria are established among conjugated and unconjugated isomers of two β-substituted styrenes, 1-phenylbut-1-ene and 1-phenyl-3-methylbut-1-ene, and one α,β-disubstituted styrene, 2-phenyl-5-methylhex-2-ene, over a range of temperatures (the van't Hoff method) in hexamethylphosphoric triamide and potassium tert-butoxide. From the trans styrenes of the first two sets, an enthalpy of conjugative interaction of phenyl vis-a-vis alkyl (ΔΔH(ConjInter/Alk)) = -2.5 ± 0.2 kcal/mol [-5.1 kcal/mol defined as phenyl vis-a-vis hydrogen (ΔΔH(ConjInter/H))] is observed, while the cis styrenes reveal an attenuated ΔΔH(ConjInter/Alk) of -1.1 kcal/mol (ΔΔH(ConjInter/H)) = -2.7 kcal/ mol). The α-methyl group in the third set also leads to a reduced conjugative interaction. Entropy plays an important role in determining positions of equilibrium. Free energies of conjugation are reported for several sterically hindered o-methyl-substituted styrenes.
- Von Doering,Benkhoff, Johannes,Carleton, Peter Smart,Pagnotta, Marco
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p. 10947 - 10955
(2007/10/03)
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- 1-Phenyl-3-amino-1,2,3,4-tetrahydronaphthalenes and Related Derivatives as Ligands for the Neuromodulatory ?3 Receptors: Further Structure-Activity Relationships
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A series of 1-phenyl-3-amino-1,2,3,4-tetrahydronaphthalenes (1-phenyl-3-aminotetralins, PATs) previously was found to stimulate tyrosine hydroxylase activity and dopamine synthesis in rat brain through interaction with a novel ?3 receptor.Speci
- Wyrick, Steven D.,Booth, Raymond G.,Myers, Andrew M.,Owens, Constance E.,Bucholtz, Ehren C.,et al.
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p. 3857 - 3864
(2007/10/02)
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- SINGLE-PARAMETER VERSUS DUAL-PARAMETER CORRELATION FOR RADICAL REACTIONS. ADDITION OF BROMINE ATOMS TO α-METHYLSTYRENES
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A rigorous procedure was developed for measuring the relative rates of addition of bromine atoms to eleven substituted α-methylstyrenes (1-Y, with Y = CF3, NO2, F, CN, Cl, Br, CO2Me, Me, COMe, OMe and SMe).The reaction was run in tetrahydrofuran in the presence of HBr, O2 and dibutyl peroxyoxalate at 30 deg C.All products were derived from the YC6H4CMeCH2Br adduct radicals, which were immediately intercepted by O2.Correlation analysis of all the data confirmed the proposition that in the absence of measurable steric effects, the relative rates for radical additions can be correlated only by a dual-parameter equation and not by a single parameter equation.Among various combiations of ?* and ξx, the (?JJ* + ?mb) combination yields the best correlation.
- Jiang, Xi-Kui,Liu, Wayne Wei-Zhong,Wu, Shi-Hui
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- Oxidative Halo-Decarboxylation of α,β-Unsaturated Carboxylic Acids
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A procedure for oxidative halo-decarboxylation of α,β-unsaturated carboxylic acids using iodosylbenzene, or iodosylbenzene diacetate, and N-chloro-, N-bromo-, or N-iodosuccinimide is presented.Good yields of the corresponding bromoalkenes are obtained when the α,β-unsaturated carboxylic acids are substituted with an aromatic substituent in the β-position and N-bromosuccinimide is used as the halogenation reagent.The scope of mainly the oxidative bromo-decarboxylation reaction is presented, and a tentative mechanism is proposed.
- Graven, Anette,Joergensen, Karl Anker,Dahl, Soeren,Stanczak, Andrzej
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p. 3543 - 3546
(2007/10/02)
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- Acyclic Stereocontrol through the Thio-Claisen Rearrangement of Precursors bearing a Chiral Centre adjacent to Carbon 1
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The Claisen rearrangement of precursors bearing a stereogenic centre adjacent to carbon 1 of the pericyclic nucleus has been investigated in the sulfur series.Dithioesters having a methyl and various alkyl or alkenyls groups on the β-carbon were deprotonated by LDA.The resulting enethiolates were allylated on sulfur to give S-allyl ketenedithioacetals.The thio-Claisen transposition of the latter compounds was achieved either at room temperature or at 101 deg C to afford good yield of allylated dithioesters.Diastereomeric selectivities up to 95:5 have been observed.These results have been explained by a steric effect and correlated to allylic strain values.
- Desert, Stephane,Metzner, Patrick,Ramdani, Mohamed
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p. 10315 - 10326
(2007/10/02)
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- Synthesis of Mono and gem-Dihalogeno-olefins from Carbonyl Compounds and in situ Generated Lithium Carbenoids
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The treatment of carbonyl compounds (5) with dihalogenomethane and lithium dicyclohexylamide at -78 deg C leads after acid hydrolysis to the crude alcohols (6), which by silylation with trimethylchlorosilane-hexamethyldisilazane-pyridine affords the crude
- Barluenga, Jose,Fernandez-Simon, Jose L.,Concellon, Jose M.,Yus, Miguel
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p. 691 - 694
(2007/10/02)
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- A convenient preparation of mono- or gem-di-halogenoalkanes from α-sulfonyl carbanions and halogenolithiocarbenoids.
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Various α-sulfonyl carbanions have been shown to react at low temperature with di- or tri-halogenolithiocarbenoids, to give 1-mono- or 1,1-di-halogenoalkanes.Bromocarbenoids gave better results than their chloro-analogues.Reaction of dibromolithiomethane with α-lithiated sulfones gives a high yield of vinylic bromides, the stereochemistry of which is cleanly E.Evidence is presented that the carbenoid itself is responsible for the reaction, and is not first converted into the corresponding carbene.
- Charreau, Philippe,Julia, Marc,Verpeaux, Jean-Noel
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p. 201 - 210
(2007/10/02)
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- Synthesis of Isomerically Pure (E)- and (Z)-1,3-Disubstituted 1,3-Dienes
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The (E)-dienes 1a - p were prepared in >98percent purity by dehydrative decarboxylation of the corresponding 4,5-unsaturated 3-hydroxycarboxylic acids 3 with dimethylformamide dimethylacetal (11).The (Z)-isomers 6a - m were obtained by stereouncontrolled
- Mulzer, Johann,Bruentrup, Gisela,Kuehl, Uwe,Hartz, Georg
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p. 3453 - 3469
(2007/10/02)
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- Reactions of Copper(I) Halide Complexes of Trivalent Phosphorus with Vinylic Halides
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The direct formation of the vinylic carbon to phosphorus bond has been accomplished via reaction of vinylic halides with copper(I) halide complexes of trialkyl phosphites.In addition, formation of varying amounts of vinylic chlorides may be observed if the reaction is performed by using vinylic bromides with copper(I) chloride complexes of trialkyl phosphites.This halogen-exchange reaction may be made synthetically useful through the employment of copper(I) chloride complexes of triaryl phosphites or phosphines.
- Axelrad, George,Laosooksathit, Surin,Engel, Robert
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p. 5200 - 5204
(2007/10/02)
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